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      1 // Copyright 2013 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 #include "chrome/browser/media/media_device_id_salt.h"
      5 
      6 #include "base/base64.h"
      7 #include "base/prefs/pref_service.h"
      8 #include "base/rand_util.h"
      9 #include "chrome/browser/profiles/profile_io_data.h"
     10 #include "chrome/common/pref_names.h"
     11 #include "content/public/browser/browser_thread.h"
     12 
     13 using content::BrowserThread;
     14 
     15 namespace {
     16 
     17 std::string CreateSalt() {
     18   std::string salt;
     19   base::Base64Encode(base::RandBytesAsString(16), &salt);
     20   DCHECK(!salt.empty());
     21   return salt;
     22 }
     23 
     24 }  // namespace
     25 
     26 MediaDeviceIDSalt::MediaDeviceIDSalt(PrefService* pref_service,
     27                                      bool incognito) {
     28   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
     29 
     30   if (incognito) {
     31     incognito_salt_ = CreateSalt();
     32     return;
     33   }
     34 
     35   media_device_id_salt_.Init(prefs::kMediaDeviceIdSalt, pref_service);
     36   if (media_device_id_salt_.GetValue().empty())
     37     media_device_id_salt_.SetValue(CreateSalt());
     38 
     39   media_device_id_salt_.MoveToThread(
     40       BrowserThread::GetMessageLoopProxyForThread(BrowserThread::IO));
     41 }
     42 
     43 MediaDeviceIDSalt::~MediaDeviceIDSalt() {
     44 }
     45 
     46 void MediaDeviceIDSalt::ShutdownOnUIThread() {
     47   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
     48   if (incognito_salt_.empty())
     49     media_device_id_salt_.Destroy();
     50 }
     51 
     52 std::string MediaDeviceIDSalt::GetSalt() const {
     53   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
     54   if (incognito_salt_.size())
     55     return incognito_salt_;
     56   return media_device_id_salt_.GetValue();
     57 }
     58 
     59 void MediaDeviceIDSalt::RegisterProfilePrefs(
     60     user_prefs::PrefRegistrySyncable* registry) {
     61   registry->RegisterStringPref(
     62       prefs::kMediaDeviceIdSalt,
     63       std::string(),
     64       user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
     65 }
     66 
     67 void MediaDeviceIDSalt::Reset(PrefService* pref_service) {
     68   pref_service->SetString(prefs::kMediaDeviceIdSalt,
     69                           CreateSalt());
     70 }
     71